1. Field of the Invention
This invention relates to a navigation apparatus for generating and providing a guide information about a target destination point to a driver of an automobile or a car by means of either or both of a voice on a speaker and a display on a screen while the automobile incorporating the navigation apparatus is in motion, and more particularly relates to a navigation apparatus which is capable of generating and providing generated guide information to a driver by means of a display based on the driver's request.
2. Description of the Prior Art
A conventional navigation apparatus detects when an automobile having the navigation apparatus becomes within a specified range of an intersection, and then informs the driver of an advancing direction to take at the intersection by means of a voice, or a voice and a visual display, as disclosed in Japanese Published Un-examined Patent Application (or in Japanese Laid Open Patent Un-examined Application) No. 202307/85 (Tokkai-Sho 60-202307).
Since the conventional navigation apparatus provides guide information to the driver independently from the driver's request or the driver's will by means of the conventional navigation system while the automobile is running, the driver does not always obtain guide information when the driver wants to get it. For example, since the guide information concerning an intersection is not provided to the driver until the automobile is close to the intersection, it is often difficult for the driver to make advance decision. If guide information is provided every specified distance or every specified time so as to solve the aforementioned problem, the driver can become annoyed and unnecessarily stressed because he hears the guide information even when he does not want it. That is to say, since the conventional navigation apparatus supplies the guide information to the driver regardless of his will, there is a problem that the driver must wait to get the guide information until the conventional navigation apparatus incorporated in the automobile provides the guide information to the drive even if the driver wants to hear the guide information.
In order to solve the conventional problem described above, another conventional navigation apparatus, for example which is disclosed in Japanese Published Laid Open Un-examined Patent Application No. 99678/93 (Tokkai-Hei 5-99678), is constructed so as to output guide information along a predetermined route by means of a voice in response to the manipulation of a driver when requested. But, since the amount of information which can be expressed by voice is relatively small, the conventional navigation apparatus has a drawback in that it cannot always supply the guide information to the driver when the driver wants precise and detailed guide information. For example, this conventional navigation apparatus has the following drawback:
Although the conventional navigation apparatus can provide guide information about a road intersection to a driver, the guide information provided by the conventional navigation apparatus typically only includes simple directions such as "Turn to the right" or "Turn to the left" by means of a voice about a point where there is the road intersecting to which several roads having oblique angles are gathered. However where there are a plurality of roads with a similar azimuth toward which the automobile having the conventional navigation apparatus can enter, it is difficult for the driver to select the road and the driver will often be at a loss to determine which road to enter.
In addition, the guide information which drivers typically want is not only a direction to turn to the right or the left, but also includes various guide information items such as a name of a point, the existence of a facility or the like on a road side by which the driver can specify the point, and the name and route number of a road to enter. Consequently, there is also a problem that it is not sufficient to supply a guide information to the driver only by means of a voice based on a driver's request.